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Still Shaking After 25 Years . . .

October 7, 2002, is the 25th anniversary of the passage of the Earthquake Hazards Reduction Act of 1977, which created the National Earthquake Hazards Reduction Program--better known as NEHRP.

In the 25 years since NEHRP was created, scientists have made significant strides in the understanding of earthquake mechanics and of how people can live safely on our dynamic planet. We have made progress in:

Hazard assessment--the vital connection between earthquake science and the actions needed to mitigate seismic risk. USGS has developed and refined the national and regional Seismic Hazard Maps. These maps of earthquake shaking hazards provide information that is essential to creating and updating the seismic design provisions of building codes used in the United States. Buildings, bridges, highways, and utilities built to meet modern seismic design provisions are better able to withstand earthquakes, not only saving lives but also enabling critical activities to continue with less disruption. The current maps were developed in 1996; USGS scientists have been working with colleagues for the past year to revise and update the maps, which include a digital database of expected ground-shaking levels at more than 150,000 sites. The revised versions are expected to be released during Fall 2002.
Earthquake monitoring and reporting--The USGS has responsibility for monitoring and reporting earthquake activity in the United States and worldwide. This task is accomplished through regional, national, and global networks of seismic monitoring stations, with strong support from many partners. Recent major improvements in instrumentation are leading to the Advanced National Seismic System, a nationwide network of at least 7000 shaking measurement systems in urban areas that will provide critical information to first responders, engineers, and researchers. Key products of the ANSS are Internet-enabled maps (ShakeMaps) that portray regional severity and distribution of ground shaking. These maps, in popular GIS formats, enable emergency responders and utility/transportation system operators to assess quickly areas of likely damage and allocate resources. ShakeMap is now an integral component of emergency response plans in several metropolitan areas (for example, Los Angeles, the San Francisco Bay Area, Salt Lake City, and Seattle), and is expanding to other regions, such as Anchorage. Complementing ShakeMaps are Did You Feel It maps, which allow citizens to report how much shaking they felt after an earthquake. These interactive Web-based maps provide the public with a forum to communicate experiences, assess impact, and learn more about earthquake activity.
Paleoseismology--finding evidence of prehistoric earthquakes in exhumed fault traces, drowned coastlines, and exposed riverbanks. Our knowledge of earthquake history in the United States is limited to a few hundred years at best -- far too short to have a true understanding of how often large damaging earthquakes may occur. Paleoseismologic investigations along active faults will extend our knowledge of past earthquakes back thousands of years, improving our knowledge of the repeat times of earthquake faults.
Geodetic applications of GPS technology. Last July, a network of 250 continuously operating GPS stations in Southern California was completed; this project was a partnership between USGS, NASA/Jet Propulsion Lab, Southern California Earthquake Center, and Scripps Institution of Oceanography at UCSD, with additional funding from the William Keck Foundation and NSF. The goals of the network are to
- measure crustal movement for better estimating earthquake potential
- identify active blind thrust faults
- measure local variations in strain
- measure permanent crustal deformation after an earthquake
The data are freely available over the Internet and are used by scientists, engineers, surveyors, and others. Find out more at http://geopubs.wr.usgs.gov/fact-sheet/fs069-01/

The purpose of NEHRP is to reduce the risks of life and property from future earthquakes. The USGS, the National Science Foundation, the National Institute of Standards and Technology, and the Federal Emergency Management Agency are the four primary NEHRP federal partners; FEMA has been designated the lead agency, with responsibility for planning and coordinating the Program.

Links to USGS earthquake information

General information about USGS Earthquake Hazards Program

Earthquakes by State

Today in Earthquake History
Find out what significant earthquakes occurred today--or any day!

Preparing for an earthquake

Earthquake facts and lists

Earthquake photographs

National Earthquake Hazard Reduction Program (NEHRP) Maps -- These maps are based on the USGS probabilistic hazard maps with additional modifications incorporating deterministic ground motions in selected areas and the application of engineering judgment.

Still Shaking After 25 Years . . .

Links to USGS earthquake information

Other earthquake links